Species

Justification
This species has a small range, and remaining tracts of its forest habitat are severely fragmented and under great pressure outside protected areas. Its population is therefore suspected to be declining and it is listed as Vulnerable.

Taxonomic source(s)
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

Taxonomic note
Bubo poensis and B. vosseleri (Sibley and Monroe 1990, 1993) are retained as separate species contra Dowsett and Forbes-Watson (1993) who include vosseleri as a subspecies of B. poensis.

Identification
48 cm. Large, "eared" owl of forest. Heavily barred, richly-coloured upperparts. Pale underparts, heavily splotched on breast but finely barred on belly and flanks. Orange-brown eyes. Similar spp. Spotted Eagle-owl B. africanus is smaller, with white spotting on wing-coverts, white mantle-edging, and yellow eyes. Voice Series of low pop pop pop notes, rising and falling in crescendo and speed. Hints Forest and forest-edge. 

Distribution and population
Bubo vosseleri is distributed throughout the Eastern Arc Mountains of Tanzania, having been recorded from both the East and West Usambara Mountains (including Mt Nilo Forest Reserve (Cordeiro 1998; Seddon et al. 1999a), Uluguru North Forest Reserve (above Tegetero; Hunter et al. 1998), Mkungwe Forest Reserve (15 km north-east of the Ulugurus and particularly common; D. C. Moyer and E. A. Mulungu in litt. 1999), Iwonde Forest in Udzungwa Mountains National Park (T. Butynski in litt. 1999), Kilombero Nature Reserve (Mt Mufu) (Barnes et al. 1999), and Uzungwa Scarp Forest Reserve (along the Kihanga and Mpimbili rivers and in the Mbawi sector; D. C. Moyer and E. A. Mulungu in litt. 1999). There are also unconfirmed reports or probable records from three other locations (J. Fjeldså in litt. 1998; Moreau 1964; D. C. Moyer and E. A. Mulungu in litt. 1999; T. Romdal in litt. 1998). Records from lowland forest in the Usambaras during October-March (Evans 1997b; D. C. Moyer and E. A. Mulungu in litt. 1999) suggest that it may be resident there and the total population may thus be higher than the previous estimate of 200-1,000 individuals (Evans 1997b).

Population justification
The population has been estimated at 200-1,000 individuals, however records from lowland forest in the Usambaras (D. C. Moyer and E. A. Mulungu in litt. 1999) suggest that the total population is higher. The population is therefore placed in the range 2,500-9,999 individuals. This equates to 1,667-6,666 mature individuals, rounded here to 1,500-7,000 mature individuals.

Trend justification
The species's habitat is being cleared and degraded through encroachment for subsistence agriculture, timber extraction and grazing by livestock (Cordeiro 1998), and is declining slowly (N. Burgess in litt. 2007); therefore the population is suspected to be in decline.

Ecology
Most records are from montane and submontane evergreen forest (800-1,500 m), with some from lowland evergreen forest down to 200 m (Zimmerman et al. 1996). It is presumed to be a canopy-dwelling species (Zimmerman et al. 1996). It may be able to tolerate some human disturbance of forest structure, since it occurs on the forested borders of tea plantations (Zimmerman et al. 1996), and several young birds have been found in forest where the understorey has been cleared for cardamom cultivation. The diet appears to be exclusively small mammals (rodents, insectivores and possibly dwarf bushbabies Galagoides; T. Butynski in litt. 1999; D. C. Moyer and E. A. Mulungu in litt. 1999). The breeding season is thought to be November-February. The nest-site may be a tree-hole.

Threats
Unreserved forests in the East Usambaras are under heavy pressure from subsistence agriculture, pit-sawing and grazing livestock (Cordeiro 1998), although most forests in this region have been gazetted as protected areas since 1997-2004 (N. Burgess in litt. 2007). There is also pressure on forest reserves in many areas and this is likely to increase as stocks of fuelwood and timber outside reserved areas are depleted (Cordeiro 1998; Seddon et al. 1999a).

Conservation actions underway
CITES Appendix II. The East Usambara Catchment Forest Project is curbing forest destruction and incorporating much of the remaining unprotected forest into reserves, e.g. at Mt Nilo Forest Reserve (Cordeiro 1998). However, the lack of jurisdiction over neighbouring Public Lands Forest threatens the long-term prospects of reserves (Cordeiro 1998). Conservation action in the Ulugurus focuses on assisting local initiatives and increasing the involvement of local communities in forest management (Buckley and Matilya 1998). Iwonde Forest in Udzungwa National Park is well protected (T. Butynski in litt. 1999).

Conservation actions proposed
Conduct surveys to establish population densities and sizes at known locations (D. C. Moyer and E. A. Mulungu in litt. 1999; Seddon et al. 1999a). Establish a programme to monitor its population and habitat on a regular basis (Seddon et al. 1999a). Improve the protection and management of reserves within the species's range. Continue to increase the involvement of local people in forest management.

References
Moreau, R. E. 1964. The re-discovery of an African owl Bubo vosseleri. Bulletin of the British Ornithologists' Club 84: 47-52.

Zimmerman, D. A.; Turner, D. A.; Pearson, D. J. 1996. Birds of Kenya and northern Tanzania. Helm, London.

Evans, T. D. 1997. Records of birds from the forests of the East Usambara lowlands, Tanzania, August 1994 - February 1995. Scopus 19: 92-108.

Hunter, N.; Carter, C.; Mlungu, E. 1998. A new location for the Usambara Eagle Owl Bubo vosseleri. Scopus 20: 52-53.

Cordeiro, N. J. 1998. A preliminary survey of the montane avifauna of Mt Nilo, East Usambaras, Tanzania. Scopus 20: 1-18.

Buckley, P.; Matilya, J. G. 1998. Saving Tanzania's mountain forests. World Birdwatch 20: 16-19.

Barnes, J.; Barnes, R.; Burston, P.; Githiru, M.; Leckie, J.; Mulwa, R.; Pilgrim, J. 1999. Project Kasigau '98.

Seddon, N.; Ekstrom, J. M. M.; Capper, D. R.; Isherwood, I. S.; Muna, R.; Pople, R. G.; Tarimo, E.; Timothy, J. 1999. Notes on the ecology and conservation status of key bird species in Nilo and Nguu North Forest Reserves, Tanzania. Bird Conservation International 9: 9-28.

Further web sources of information
View photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Ekstrom, J., Evans, M., Shutes, S., Starkey, M., Symes, A., Taylor, J.

Contributors
Burgess, N., Butynski, T., Fjeldså, J., Moyer, D., Mulungu, E., Romdal, T.

IUCN Red List evaluators
Butchart, S., Taylor, J.

Recommended citation
BirdLife International (2013) Species factsheet: Bubo vosseleri. Downloaded from http://www.birdlife.org on 23/05/2013. Recommended citation for factsheets for more than one species: BirdLife International (2013) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 23/05/2013.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

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Additional resources for this species

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